So-called "hair extensions" are widely advertised, including through television "infomercials," and in general, are used to add to or otherwise augment the hair of the user so as to cover bald spots or areas where the hair is thinning, to produce different styling effects, or to simply add to the shape or fullness of the existing hair. The new hair is supported on the head of a user in a number of different ways including bands, clips and caps which are secured to or fit over or around the head.
A hairpiece or hair extension of particular interest here is that disclosed in U.S. Pat. No. 4,600,029 to Ueberschaar. This patent discloses a hairpiece comprising a plurality of individual hairs adjustably secured around an endless circular filament or filaments referred to as a filamentary circlet. The circlet fits over and around the head and the individual hairs hang down therefrom. The individual hairs are knotted to the circlet and can be adjustably moved to the desired location so that, for example, the hair can be moved to a location where the natural hair is thin.
A disadvantage of this type of hairpiece is that the circlet, being an endless loop, is of a fixed diameter so that it will fit or lie differently on different wearers depending on the size of their heads. Thus, the overall effect produced by the hairpiece can differ widely for different wearers. For example, where fullness is required in a particular area to simulate a specific hairstyle, it may not be possible to achieve such fullness in that area where the circlet sits up high upon the head for a wearer with a large head or is disposed very low down on the head for a wearer with a small head.
Providing adjustability in such a circlet presents problems. For example, the filament is difficult to work with because of its very small diameter. Further, any adjustment device provided must be very small so as to be virtually invisible and completely unobtrusive in the hair. In additional and perhaps more importantly, it is critical that any adjustment to be made be "semi-permanent" in the sense that once a particular diameter is selected it should remain fixed, within limits. In this regard, it would obviously be highly undesirable for the circlet to inadvertently expand and slip in place on the head of the wearer. However, on the other hand, the first diameter selected should not be completely permanent or fixed, after selection, in the event that the wearer should desire to change the diameter for whatever reason (e.g., to effect a different hair style). Thus, the capability of further adjustment must be maintained despite the need for a "semi-permanent" fixing of each diameter selected. Moreover, the adjustment device should be inexpensive, durable and easy to use.